Most plants require daily or weekly watering. Some people even give their plants extra nutrients with such products as 'Miracle Grow'. House plants may even come with directions as to how much sunlight, shade and water the plant needs to survive. So how do cacti that live in the desert survive by being deprived of water and nutrients? Through evolution these special plants have adapted ways to overcome their environment and predators.

Cacti are photosynthetic just like other plants; they use the sun for energy to grow. The body of a cactus actually swells in times of moisture so that it can store the much needed water for later. In times of drought the body sinks in, or contracts. The most distinct part of a cactus is its spines. Because regular leaves don't conserve water well, the cactus developed these modified leaves to adapt to its extremely dry environment. The spines are better at conserving water and surviving in hot temperatures. Regular leaves provide a large surface area for evaporation of water to occur, the tiny spines do not. The spines actually collect moisture from the air and let it drip down to the roots of the cactus. Also, spines are used to ward off predators. Would you want to eat something that is prickly?

It is a misconception that cacti actually live in true deserts where the ground is all sand. Most live in a sandy environment with very little soil, but enough for some limited nutrients to be found. Cacti are usually found in semi-desert regions and dry grasslands. One of the benefits of living in an arid region is that the cacti have no competition for the limited amount of nutrients in the ground because most other plants cannot survive in the harsh environment. If the environment does become too harsh for the cacti, they simply become dormant and grow again when there is moisture. Cacti are real survivors, packed full with evolutionary adaptations to endure their environments. They are probably one of the luckiest plants around.

259

About the Author

Rebekah ShafferRebekah Shaffer is currently a Junior at Slippery Rock University, PA. She is pursuing her B.S. in Biology, minor in Chemistry. She currently works as a microbiology lab assistant at Slippery Rock University and is a member of Beta Beta Beta Biology Honorary Society. She plans to obtain her Ph.D. in Molecular/Cellular Biology after completing her undergraduate degree.